A novel ion imager for secondary ion mass spectrometry

An area detector for a secondary ion mass spectrometry (SIMS) ion microscope and its performance are described. The operational principle is based on detecting the change in potential of a floating photodiode caused by the ion-induced secondary-electron emission and the incoming ion itself. The experiments demonstrated that 10¹-10⁵ aluminum ions per pixel can be detected with good linear response. Moreover, relative ion sensitivities from hydrogen to lead were constant within a factor of 2. The performance of this area detector provides the potential for detection of kiloelectronvolt ion images with current ion microscopy     

The effect of annealing temperatures on self-aligned replacement (damascene) TaCN-TaN-stacked gate pMOSFETs

In this paper, we report the first self-aligned replacement (Damascene) TaCN-TaN-stacked gate electrode pMOSFETs. The high-temperature (>1000/spl deg/C) implant activation anneal was done prior to the metal electrode deposition. After the fabrication was completed, the transistors were then annealed at lower temperatures (300/spl deg/C-600/spl deg/C), which might affect the critical device parameters, such as subthreshold slope, threshold voltage, gate leakage, on, and off currents. Our data show that TaCN is a promising material for the metal-gate pMOSFETs due to the suitable metal work function and good thermal stability up to 500/spl deg/C, which is much higher than the highest temperature required by the backend very large-scale integration process.     

High-performance coherent demodulator LSIC for wireless personalcommunications

This paper presents a high-performance coherent π/4-shift differential quaternary phase shift keying (DQPSK) demodulator (large scale integrated circuit) LSIC for the personal communication system in Japan, which is implemented on a 2-V operation 0.8-μm CMOS standard cell. The developed LSIC achieves a better bit error rate (BER) and frame error rate (FER) performance and a lower power consumption than conventional demodulators by employing new schemes: (1) a reverse-modulation carrier recovery circuit with a -π/4 phase rotator and a bandwidth-changeable carrier filter; (2) a bit timing recovery circuit using an initial bit timing estimation scheme; and (3) a fully digital orthogonal detector suitable for low power consumption. Performance evaluation confirms that the developed demodulator LSIC reduces the irreducible frame error rate by 40% and achieves an Eb/No improvement of 3 dB at an FER of 10^-1 compared with differential detection in the Rayleigh fading typical of personal communication channels     

Quasi-phase-matched second-harmonic generation by backwardpropagating interaction

Both static and dynamical analyses of quasi-phase-matched second-harmonic generation by backward propagating interaction, where the second-harmonic wave is generated in reflection, are presented. It is shown that bistability appears in the generated second-harmonic power if the amount of phase mismatch is suitably chosen. The bistability also appears in the output fundamental wave, since the cascaded second-order nonlinear process gives rise to the effective self-modulation of the fundamental wave, which can be applied to all-optical signal processing. The output second-harmonic and fundamental powers can be switched between two bistable states by controlling the intensity or phase of the input fundamental wave     

Syntheses and X-ray structures of mixed benzenethiolato-sulfido and -selenido trinuclear nickel clusters

The reaction between NiCl₂, NaSPh and NaEH (E = S, Se) in a mixture of acetonitrile and acetone gave trinuclear clusters [Ni₃(μ₃-E)(μ-SPh)₃(SPh)₃]²⁻(E = S, Se) and the previously characterized mononuclear complex [Ni(SPh)₄]²⁻. The X-ray structures of the trinuclear clusters are similar to each other except for the Ni₃E (E = S, Se) sections, and the Ni---E (E = S, E = S, Se) frameworks planes which are condensed via adjacent edges to form planar NiS₄ or NiS₃Se coordination planes which are condensed via adjacent edges to form cyclic systems with a triply bridging sulfido or selenido ion in the centre.     

Permeability of glycosides through human erythrocyte membrane

The permeability of glycosides (arbutin, salicin, glycyrritin, p-nitrophenyl-beta-D-glucopyranoside, p-nitrophenyl-beta-D-galactopyranoside, p-nitrophenyl-beta-D-lactopyranoside, p-nitrophenyl-beta-D-maltopyranoside) and their aglycons through human erythrocyte membrane was investigated. The glycosides permeated slowly, compared with their aglycons. Glycoside having disaccharide did not permeate the erythrocyte membrane. This suggested that the introduction of disaccharide to a drug significantly depresses the permeability of glycoside through erythrocyte membrane. The drug entrapped in erythrocytes was not released into the outer medium.     

PHOTOCHEMICAL COUPLING OF 5-BROMOURACIL TO TRYPTOPHAN, TYROSINE AND HISTIDINE, PEPTIDE-LIKE DERIVATIVES IN AQUEOUS FLUID SOLUTION

Direct irradiation of 5-bromouracil (BU) in aqueous fluid solution in the presence of tryptophan (trp), tyrosine (tyr) or histidine (his) derivatives using a XeCl excimer laser at 308 nm yielded photocoupling of BU to the aromatic ring of each amino acid. Irradiation of BU at 308 nm most likely results in excitation of the n-φ* transition, intersystem crossing to the triplet manifold, and coupling via electron transfer from the aromatic amino acid. The coupling observed was regiospecific between the 5-position of uracil (U) and the 2-position of the indole and phenol rings and the 5-position of the imidazole ring of the respective amino acids. Quantum yields of photocoupling to BU ranged from 1 × 10^-3 to 7 × 10^-3 and paralleled known rates of electron transfer and ionization potentials of the aromatic rings. The photocoupling between BU and some of the aromatic amino acid peptide-like derivatives possibly mimics photocrosslinking of BU-DNA to associated proteins, a potentially useful photoreaction for studying nucleic acid-protein interactions. Formation of crosslinks of the type proposed here might be detected by the characteristic fluorescence emission of the uracil amino acid adducts.     

RECa4O(BO3)3 thin films as new Luminescent materials screened by the combinatorial method

A new phosphor material, Y_1−xTb_xCa₄O(BO₃)₃ (0≤x≤1) film was grown on SiO₂ substrates by the combinatorial pulsed laser deposition (PLD) method, which enabled us to fabricate continuous composition spread film libraries. Photoluminescence (PL) and PL decay were measured for these film libraries to identify the optimum composition as well as to determine the luminescence mechanism. The film libraries showed strong dependence of luminescence intensities on the chemical composition of Tb ion. The optimum concentration of Tb ions in Y_1−xTb_xCa₄O(BO₃)₃ was experimentally and theoretically determined to be x=0.2-0.3.